To migrate OpenShift v2 applications to OpenShift Container Platform v3, all cartridges in
the v2 application must be recorded as each v2 cartridge is equivalent with a
corresponding image or template in OpenShift Container Platform v3 and they must be migrated
individually. For each cartridge, all dependencies or required packages also
must be recorded, as they must be included in the v3 images.

The general migration procedure is:

Back up the v2 application.

Web cartridge: The source code can be backed up to a Git repository such as by
pushing to a repository on GitHub.

Database cartridge: The database can be backed up using a dump command
(mongodump, mysqldump, pg_dump) to back up the database.

The snapshot is a tar file that can be unzipped, and its content is application source code and the database dump.

If the application has a database cartridge, create a v3 database application,
sync the database dump to the pod of the new v3 database application, then
restore the v2 database in the v3 database application with database restore
commands.

For a web framework application, edit the application source code to make it v3
compatible. Then, add any dependencies or packages required in appropriate files
in the Git repository. Convert v2 environment variables to corresponding v3
environment variables.

Create a v3 application from source (your Git repository) or from a
quickstart with your Git URL. Also, add the database service parameters to the
new application to link the database application to the web application.

In v2, there is an integrated Git environment and your applications
automatically rebuild and restart whenever a change is pushed to your v2 Git
repository. In v3, in order to have a build automatically triggered by source
code changes pushed to your public Git repository, you must set up a
webhook
after the initial build in v3 is completed.